Hydrofoil craft



-C- 6, 1954 G. J'. wl-:NNAGEL ETAL 3,151,593.

HYDROFOIL CRAFT 2 Sheets-Sheet 1 Filed Feb. 4, 1965 ImNToRs GLENFORD J. WENNAGEL ALQUST C. SARRANTONIO ZM/' ATTORNEY United States Patent O 3,151,593 HYDROFL CRAFT Glenford Joseph Wennageh Huntington, and August C.

Sarrantonio, Huntington Station, NX., assignors to Grumman Aircraft Engineering Corporation, Bethpage,

N.Y., a corporation of New York Filed Feb. 4, 1963, Ser. No. 255,332 9 Claims. (Cl. 114-665) This invention relates 'to improvements in hydrofoil craft and, in particular, relates to means for automatically adjusting the lift characteristics of the hydrofoils for achieving proper depth control of the hydrofoils.

Hydrofoil craft are generally provided with submerged hydrofoils or supporting hns inclined at a suitable angle of incidence so that upon the craft attaining a predetermined speed it is supported above its normal iloating position at a distance above the water surface by the lift generated by the submerged hydrofoils.

There are several methods for controlling the depth of submergence of the hydrofoils to regulate the clearance of the hull of the hydrofoil craft above the water. As is well known in the art, where hydrofoils of the surfacepiercing type are used, depth control is eected through the shape of the hydrofoil itself, in that lift is dependent on depth of submergence.

The same principle is sometimes used by arranging an array of lifting surfaces at dilferent superimposed levels such that the number of surfaces submerged increases with the depth of submergence so to thereby increase the lift.

Because of a number of inherent disadvantages of such arrangement, submerged hydrofoil systems using hydrofoil sets and some means for depth control are increasingly employed in the art.

lt has already been proposed in craft of 'the submerged hydrofoil type that an autopilot be used to control the angle of attack of the hydrofoil or the position of a flap associated with the hydrofoil to thereby control the lift and hence the depth of submergence of (the hydrofoil. However, because of the complexity required in the design of such systems to insure the levels of effectiveness and reliability in autopilots for this service, their cost and maintenance requirements have militated against their use.

Another approach proposed in the prior art to this problem of depth control has been the provision of a control plane or oat which floats or skirns `on the surface of the Water and which is normally disposed ahead of the hydrofoii which it controls. The object of the control plane or oat is to predict the Wave formation ahead of the craft and by suitable linkage to vary the lift of the hydrofoil by varying its angle of attack or by actuating a ap associated with the hydrofoil. The disadvantages of this known system of water surface prediction are the vulnerability of the jockey arms usually employed in the mechanical linkage, as well as in the design diculties posed in incorporating an effective hydrofoil retraction mechanism with such an arrangement. Funthermore, at speed, the control planes or toats are found to impact and bounce on the waves causing objectionable levels of shock, vibration, and noise in the craft. Should the wave structure result in severe bouncing of the control means, the consequent uctuations induced in the lift of the hydrotoils adversely affects the stability of the craft.

It has also been proposed in craft of this kind to utilize water pressure or depth sensitive means located in fixed structure ahead of the craft or in the hydrofoil structure itself as wave and depth predictor means. Such predictor means serve to regulate a suitable hydrofoil control mechanism to Vary the lift of one or more of the hydrofoils such that the craft follows the undulations of the water ice surface. Such known predictor means employ electrical or other suitable regulating systems to actuate the hydrofoil controls in response to signals from the pressure sensors. By their very nature, these pressure sensors must be relatively sensitive devices and are thus vulnerable to damage by waterborne debris and marine matter. They also introduce an element of complexity in the control system that increases the lirst cost and maintenance expenses of the craft as well as reducing its reliability.

It is thus the principal object of this invention to provide a mechanically simple hydrofoil depth control system to overcome the above mentioned disadvantages of the prior art systems and to achieve novel automatic depth control means for maintaining the depth of submergence of `the hydrofoil at the desired or design level such that the hydrofoil operates at a substantially constant depth throughout a range of craft speeds.

it is a further object of this invention to provide a fully-automatic hydrofoil depth control system for maintaining the hull of the craft at the desired height above the water surface in foil-borne operation and, in the case of Waves, for maintaining a substantially constant submergence of the hydrofoils below an average Water level so that smooth transit is obtainable in rough walter.

Another object of this invention is to provide a hydrofoil depth control system which utilizes surface-piercing controller vane means to obtain a dynamic response to craft speed and sea state and in which the energy required for operation of the mechanism is derived from the energy of the travelling craft such that a separate or an auxiliaryI power supply for the system is not required.

A still further object is to provide a hydrofoil craft with a hydroioil de th control system wherein the hydrofoils or at least a portion thereof are mounted for varying the lift characteristics of the hydrofoil and including means responsive to the drag forces of the water thereon for controlling the position of the hydrofoils or such lift varying portions.

It is another object to provide a novel automatic hydrofoil depth control system which uses rugged, uncomplicated rnechanical means :to control the lift of the hydrofoil and in which fabrication, installation, and maintenance costs are substantially reduced without any compromise in performance or reliability in either normal or in extremes of operational and environmental conditions.

Still another object of this invention is `the provision of an automatic hydrofoil depth control system which can be readily accommodated in the engineering design of the hydrofoil retraction system.

Another object of this invention is to provide an automatic hydrofoil depth control system whose design penmits the incorporation of means for selectively overriding the automatic control system as desired.

Other objects and advantages will become apparent from the following descrip-tion when taken in conjunction with the accompanying drawings in which:

FIG. l is a perspective View of one of the hydrofoils of the craft from the outside and rear showing the depth control mechanism;

FiG. 2 is a side View showing the hydrofoil below the design depth of submergence;

FIG. 3 is a side view showing the hydrofoil at the design depth of submergence;

FIG. 4 is a side view of the hydrofoil depth control override mechanism.

Referring to the drawings, the instant invention is shown tted on a hydrofoil craft having a hull 1t) on which is mounted the hydrofoil l1 by means of a downwardly depending strut member .l2 of suitable streamline shape. As is Well known in the art, one or more hydrofoils 1l are provided for the dynamic support of the craft, after it gets under wa* such that the hull it? is raised entirely out of the water. When the craft is in foil-borne Voperation at its design speed, the clearance above te w ter surface is adequateY in average sea stat to avoid substantialwave impact against any portion of the hull. The particular configuration or design of 'the hull, or the arrangement or number of hydrofoils employed are not shown and will not be described in detail since such form no part of the instant invention. The craft also may be driven c-r steered in any suitable way such as by air or water screws andV rudders, wnich again do not form part of the instant invention and hence are not shown and will not be further described.V

Control of the lift of the hydrofoil il in the embodi-V ment shown is obtained by the deflection of a trailing edge flap 13 hingedly mounted on the hydrofoil .ilV by hinge means 13. lt is apparent, however, that instead of using such ap means, the hydrofoil itself may be hydrofoil, the use of the same control means to vary the.

angle of attack of the hydrofoil itself, or any portion thereof, for the same purpose is within the spirit and scope of this invention.

in the embodiment shown, the automatic control means used to actuate the ilap i3 comprises an upwardly eX- tending surface-piercing controller vane 1d. Controller vaneV 14 consists of an elongated plate l5 and a drag element 16 which is mounted on the leading edge of the.

plate. Drag element l5 may be of V section, with the leading edge of plate'l welded to the inside apex of the V as best shown in FIG. l, or may be of any other suitable configuration or size to best serve its function. The lower end17 of plate 15 is welded or otherwise suitably mounted on the upper surface l of liap i3. As la protective measure against waterborne debris, controller vane V14 may be mounted astern of and in alignment with the strut 12 las shown; however, it is obvious that the controller vane may be mounted in any other suitable loca-tion if design requirements so dictate.

In operationV when the craft is getting under way, the controller vane 14 is fully immersed as shown in FlG. 2 and is subjected to high drag by the water. The drag forces exerted on the controller vane are sullicient to overcome the forces of the water acting upwardly against the bottom surface 31 of trailing edge flap 13, thus the vane is rotated counterclockwise to depress flap 13. With the flap inV suchpositiongthe hydrofoil il will be in its configuration for producing maximurnlift. The controller vane 14 will remain substantially submerged and mainrtain the hydrofoil in the high-lift configuration -as the craftV builds up speed, thus reducing the time required to attain foil-borne operation. As the speed increases, the lift generated by the hydrofoil system raises hull of theV craft out'of the water sol that the craft attains foilborne operation. When strut 12j emerges from the water as the speed increases, the controller vane 14 also is carried upwardly toernerge from'or pierce the sur- Thus, the invention reon the flap are balanced and the system maybe considered to be in equilibrium.

Should the actual submergence of the hydrofoil at design speed momentarily exceed design submergence such as by the craft encountering a wave or swell, the area of the controller vane under water will be increased. This increases the drag of the vane and the ilapwill be deflected downwardly thereby increasing the lift of the.hy' drofoil to restore it to design submergence. Hence the craft is raised to contour a wave or swell.

Conversely, should the actuall hydrofoil submergenceV at design speedmomentarily become. less than design submergence as by encountering a trough, the area of the controller vane .under water will beV reduced; This deupwardly. This in turn'reducesthe lift of the hydrofoihl.

causingia submergence to the design depth to contour the trough.

InV the event the speed of the craft increases above the. i

design speed, the control action is as described immediately above. The decrease in drag ofthe vane brought about by the progressive emergence of thehydrofoil and vane with increasing speed permits the'ap toV deflect upwardly which results a reduction'in hydrofoil lift. This decrease iny hydrofoil lift causes ,the craft to settle to a: lower level so that the controller vane submergence is at a level where the drag forces on the vane and'on the llap balance' out and Iagain reach aV condition of equilibriurn.Vr Y

When the Vcraft encounters head seas, the closing speed of the craft with respect to those seas results in less time being available for the control system to respond.- However, under-these conditions, the upward Ycomponent of the orbital velocities of such head seas in effect iiicreases the angle of .attack of the hydrofoilr to accentuate the response to the control system. Asdescribedpreviouslyl for the condition when [the craft encounters av wave, the resultant forces exerted by the controllervane with the increase in submergence Ias the, hydfofoil enters the wave,` causes a deflection of they flap downwardly.

This increases the lift ofthe main hydrofoilto enable the'wave to be contoured.;

. In a following sea, there is, in effect, a decrease in the,l angle of attack of the hydrofoil Aas Ia result ofthe down-V ward component of the orbital velocities of such follow ing seas. This decrease in the angle of attack decreases the lift of the hydrofoil and increases its submergenceYY into the water. However, this settling also results in theI controller vane being immersed deeper in the water and the consequent build up in its dragY increases the forces thereon so as to deflect the flap downwardly. As before, this increases the lift of the hydrofoil to avoid settling in a following sea.

ln the foregoing description of the operationA of ourinvention the discussion has been confined toa single hydrofoil with itsV controller vane although werrecognizey fully that craft of this type normally are equipped with. more than one 'nydr-cfoil.Y It is apparent that whenour invention is used with hydrofoil craft having two hydrofoils, either spaced athwartshipsy on either side of the hull Y or in a tandem arrangement along the keel, automatic leveling of the craft will be provided in event some yoccur-` rence should alter the equality of submergence of the two face of the water such that the area of the vane im' mersed in the wateris reduced. A reduction in the area of the controller vane 14 immersed in the water reduces its drag and consequently reduces the forces exerted by the vane on the flap. The thrust of the water against the bottom of the hap, then being greater than the forces exerted by the vane on the ap, causes the flap to rotate upwardly until the forces again are in balance. The strut andalong with it, the vane, will continue to emerge from the water until the craft reaches'its predetermined design speed and height above the water as shown in FIG. 3:.l At this speed and height of the craft, the forces hydrofoils. Such an occurrence might be, for example, a, shift inthe Vloading of the craft, although other factors such as wave action might tend to create such a condition. It will Ialso be apparent that the automatic leveling just discussed is equally valid for rollin the athwartships hydrofoil arrangement and for pitch Vin the tandem arrangement,

In the discussion thus far, the controller vane actingV automatically in conjunction with the flap has been treated as the sole means for the control of the hydrofoil. However, height control ofthe craft in foil-borne operation` may also be achieved with the override control 19 shown F4 S in FIG. 4 acting in conjunction with the controller vane. Referring to FIG. 4, the override control 19 is seen to consist essentially of a bellcrank 2li and a push-pull control cable 21 and requisite mounting hardware. Bellcrank 2i? is pivotally mounted on strut l2 by means of a bracket 32 which is riveted or otherwise secured on the trailing edge of the strut. Bellcrank 2i) pivots about and is fastened to bracket 32 by bolt 22. The lower arm of the bellcrank incorporates a cam portion 23 which may be brought selectively into operational engagement with A the upper leading edge of controller vane i4. Cam portion 23 is suitably shaped to mipart the desired rotational displacement to controller vane 14 upon rotation of bellcrank 2t). Cam portion 23 may be provided with a facing 24 of a suitable elastomeric material to reduce wear and to dampen shock and vibration. Actuation o bellcrarik 2G is by means of push-pull control cable 2l whose lower end is pivotally connected to the upper arm 25 of the beilcrank by a pin 25 and clevis 217. Pin 25 is secured in position by a suitable locking ring 23 and may be located in any one of the transverse holes 29 drilled in spaced relationship along the longitudinal axis of the upper arm 25 of the bellcrank. As may be clearly seen by referring to FIG. 4, the mechanical advantage of the control cable with respect to the bellcrank is governed by the position of the clevis pin 25 along arm 25 and may be adjusted as required. Clevis 27 is secured to the end ot the control cable 21 in any well known manner as by barrel 30. The upper end cable 21 is connected to any suitable actuating means (not shown) for operating the cable to impart rotational movement to bellcrank 2li.

Still referring to FIG. 4, the mechanical functioning of override control 19 may be readily ascertained. Movement of control cable 21 upwardly results in a clockwise rotation of bellcrank 2li. This rotation, in turn, will impart a counterclockwise rotation to controller vane 14 when, in the course of the rotation of the bellcrank, cam portion 23 comes into contact with the controller vane. Should the control cable 21 be moved downwardly, bellcrank 20 is caused to rotate in a counterclockwise direction. This rotation relieves the pressure exerted by cam portion 23 on the controller vane 314, permitting the vane to rotate in a clockwise direction. Angular displacement of the controller vane, of course, results in a deflection of the hydrofoil iiap 13 on which the vane is Xed. Counterclockwise displacement of the vane deects the ap downwardly and clockwise displacement rotates the ap upwardly.

By using the override control, therefore, it is thus possible to override the automatic depth control system and to control collectively or selectively the depth of submergence of the hydrofoils such that a craft with athwartships disposed hydrofoils may be controlled in roll, pitch or height as for example, the craft may be banked into a turn and the like. In a craft having hydrofoils disposed in the fore-and-aft direction, the override control permits a selective control of the craft in pitch. The means used to operate the control cable which actuates the override control are not shown but it is clear such means may comprise a manually driven mechanism or any other suitable means now commonly available in the art.

Although shown and described in what is believed to be the most practical and preferred embodiments, it is apparent that departures from the specific apparatus shown will suggest themselves to those skilled in the art and may be made without departing from the spirit and scope of the invention. We therefore do not wish to restrict ourselves to the particular form of construction illustrated and described, but desire to avail ourselves of all modications that may fall within the scope of the appended claims.

Having thus described our invention, what we claim is:

l. In combination, a hydrofoil including means mounting at least a portion of said hydrofoil for varying its lift characteristics, and a vane member rigidly mounted upon and extending upwardly from said litt varying portion of said hydrofoil and responsive to the drag forces of the water thereon for controlling the position of said lift varying portion.

2. A hydroioil craft including at least one downwardly depending strut member, a hydrofoil provided on said strut member and including means mounting at least a portion thereof for varying its lift characteristics, and a vane member rigidly mounted upon and extending upwardly from said lift varying portion of said hydrofoil and responsive to the rag forces of the water thereon for controlling the position of said lift Varying portion.

3. A nydroioil craft including at least one downwardly depending strut member, a hydrofoil provided on said strut member and including means mounting said hydrofoil for varying its lift characteristics, and a va'ne member rigidly mounted upon and extending upwardly from said hydroroil and responsive to the drag forces of the water thereon for controlling the position of said hydrofoil.

4. A hydrofoil craft as dened in claim 2 wherein said lift varying portion comprises a flap hingedly mounted on the trailing edge of said hydrofoil.

5. The combination set forth in claim l wherein said lift varying portion comprises a iiap hingedly mounted on the trailing edge of said hydrofoil.

6. ln combination, a hydrofoil including means mounting at least a portion of said hydrofoil for varying its lift characteristics, and a surface-piercing controller vane rigidly mounted on and extending upwardly from said lift varying portion and adapted to deiiect said lift varying portion in response to the drag forces of the water acting on said controller vane.

7. A hydrofoil craft comprising a hull, at least one downwardly depending strut secured to said hull, a hydrofoil provided on the lower end of said strut and including means mounting at least a portion of said hydrofoil for Varying its lift characteristics, a controller vane rigidly mounted on said lift varying portion of said hydrofoil and extending upwardly with its upper end portion piercing the water surface when the craft is in foil-borne operation and adapted to deect said lift varying portion in response to the drag forces of the water acting on said controller vane.

8. A hydrofoil craft as defined in claim 7 and including selectively operated control means adapted to engage the upper end portion of said controller vane.

9. A hydrofoil craft as defined in claim 7 and including a bellcrank pivotally mounted on said strut, and actuating means connecting one arm of said bellcrank, the other arm of said bellcrank being adapted to engage the upper end portion of said controller vane.

References Cited in the le of this patent UNITED STATES PATENTS 857,951 Meacham June 25, 1907 955,343 Meacham Apr. 19, 1910 2,722,189 Hobday NOV. l, 1955 2,749,871 Scherer June 12, 1956 2,858,788 Lyman Nov. 4, 1958 3,044,432 Wennagel et al July 17, 1962 3,046,927 Lahde July 31, 1962 3,103,197 Von Schertel Sept. 10, 1963 

1. IN COMBINATION, A HYDROFOIL INCLUDING MEANS MOUNTING AT LEAST A PORTION OF SAID HYDROFOIL FOR VARYING ITS LIFT CHARACTERISTICS, AND A VANE MEMBER RIGIDLY MOUNTED UPON AND EXTENDING UPWARDLY FROM SAID LIFT VARYING PORTION OF SAID HYDROFOIL AND RESPONSIVE TO THE DRAG FORCES OF THE WATER THEREON FOR CONTROLLING THE POSITION OF SAID LIFT VARYING PORTION. 